1. Field of the Invention
The present invention relates generally to a wiring board, a semiconductor package and a semiconductor device, which have two-dimensionally arranged input/output terminals.
2. Description of the Related Art
In recent years, in place of a semiconductor device having peripheral arrangement type input/output terminals, a semiconductor device having two-dimensionally arranged input/output terminals has been developed and put to practical use, in view of the mounting on a multi-pin semiconductor device, electric characteristics, miniaturization and densification. In general, the arrangement of the input/output terminals of such a semiconductor device is determined by the function of the semiconductor device itself, and takes no great account of the connecting wiring to another semiconductor device when the semiconductor device is mounted on a wiring board, or to the input/output part of the wiring board. Also in the wiring board, there is the lower limit to wiring and connecting terminal pitch, so that there is a problem in that required wiring can not be provided on the wiring board after mounting. This is no problem in a semiconductor device having a small number of input/output terminals, such as a memory. However, in a semiconductor device having a multi-pin input/output terminal, such as a data processing circuit or a logic circuit, there is a problem in that it is difficult to make a wiring layout on a wiring board side inside of an input/output arrangement, although a signal line arranged on the terminal in the peripheral portion of the input/output arrangement can be connected to the wiring on the wiring board.
In order to solve this problem, in a conventional semiconductor device 100, terminals 102 having alternating current stable potentials, such as a power supply or a ground, are concentrated on the central portion, and input/output terminals 104 for other signals are arranged on the peripheral portion, as shown in FIG. 16. However, in such a structure, signal wirings are closely arranged on a wiring board, so that there is a problem in that it is difficult to control crosstalk and electric characteristics on the wiring board. This becomes obvious as the processed signals accelerate. In particular, it is required to control a wiring on a wiring board, on which a semiconductor device having a system""s base clock of 200 MHz or more is mounted, as a transmission line.
Thus, in conventional wiring boards or semiconductor devices, signal wirings are closely arranged, so that there is a problem in that crosstalk occurs between signals transmitted through signal wirings.
In order to prevent crosstalk from occurring, it has only to arrange power supply wirings or ground power supply wirings, which are alternating current stable, adjacent signal wirings. However, if the power supply or ground power supply wirings are arranged adjacent the signal wirings, there is a problem in that the size of the wiring board or semiconductor device increases.
It is therefore an object of the present invention to eliminate the aforementioned problems and to provide a wiring board, a semiconductor package and a semiconductor device, which can prevent the occurrence of crosstalk and the increase of the size even if signal wirings are closely arranged.
In order to accomplish the aforementioned and other objects, according to one aspect of the present invention, there is provided a wiring board having a plurality of wiring layers, wherein a plurality of signal wiring terminals and a plurality of power supply terminals are arranged on a principal plane of the wiring board, the plurality of signal wiring terminals or the plurality of power supply terminals being connected to any one layer of inner layers of the wiring layers, and wherein signal wiring terminals, which are connected to wirings formed on the same layer, among the plurality of signal wiring terminals are arranged so that at least one side of the inside and outside of a region, in which the signal wiring terminals connected to the wirings formed on the same layer are formed, is surrounded by the power supply terminals.
The power supply terminals may have ground power supply terminals and driving power supply terminals, and the power supply terminals surrounding the at least one side of the inside and outside of the region, in which the signal wiring terminals are formed, may be the ground power supply terminals or the driving power supply terminals.
The power supply terminals surrounding the at least one side of the inside and outside of the region, in which the signal wiring terminals are formed, are preferably connected to a common wiring formed on the same layer.
The number k of signal wiring terminals, which are arranged on a column extending from an edge of the wiring board toward a central portion of the wiring board, among the signal wiring terminals surrounded by the power supply terminals are preferably arranged so as to satisfy the following formula:
kxe2x89xa61+(Pxe2x88x92Axe2x88x92S)/(S+W)
wherein a size of each of the signal wiring terminals is A, a pitch between the signal wiring terminals is P, a width of each of the wirings is W, and a minimum dimension of a space between adjacent two of the wirings is S.
The power supply terminals are preferably arranged in the central portion and the outermost portion of the wiring board.
According to another aspect of the present invention, there is provided a semiconductor package having a plurality of wiring layers, wherein a plurality of signal wiring terminals and a plurality of power supply terminals are arranged on a principal plane of the semiconductor package, the plurality of signal wiring terminals or the plurality of power supply terminals being connected to any one layer of inner layers of the wiring layers, and wherein signal wiring terminals, which are connected to wirings formed on the same layer, among the plurality of signal wiring terminals are arranged so that at least one side of the inside and outside of a region, in which the signal wiring terminals connected to the wirings formed on the same layer are formed, is surrounded by the power supply terminals.
The power supply terminals may have ground power supply terminals and driving power supply terminals, and the power supply terminals surrounding the at least one side of the inside and outside of the region, in which the signal wiring terminals are formed, may be the ground power supply terminals or the driving power supply terminals.
The power supply terminals surrounding the at least one side of the inside and outside of the region, in which the signal wiring terminals are formed, are preferably connected to a common wiring formed on the same layer.
The number k of signal wiring terminals, which are arranged on a column extending from an edge of the semiconductor package toward a central portion of the semiconductor package, among the signal wiring terminals surrounded by the power supply terminals are preferably arranged so as to satisfy the following formula:
kxe2x89xa61+(Pxe2x88x92Axe2x88x92S)/(S+W)
wherein a size of each of the signal wiring terminals is A, a pitch between the signal wiring terminals is P, a width of each of the wirings is W, and a minimum dimension of a space between adjacent two of the wirings is S.
The power supply terminals are preferably arranged in the central portion and the outermost portion of the semiconductor package.
According to another aspect of the present invention, a semiconductor device comprises: a wiring board; a semiconductor package having terminals provided on the principal plane so as to correspond to terminals of the wiring board; and a semiconductor chip which is mounted on the semiconductor package and which is electrically connected to the semiconductor package, the terminals of the semiconductor package being connected to corresponding terminals of the wiring board.
According to a further aspect of the present invention, there is provided a wiring board having a plurality of signal wiring layers and a plurality of first and second power supply terminals, which are arranged on a principal plane of the wiring board, wherein at least one side of the inside and outside of a first region, in which the first power supply terminals are formed, is surrounded by the signal wiring terminals, and at least one side of the inside and outside of a second region, in which the second power supply terminals are formed, is surrounded by the signal wiring terminals.
The second region may be arranged within the first region, which may be spaced from the second region via a third region, and all of terminals arranged in the third region may be signal wiring terminals.
Preferably, the wiring board is a multilayer printed circuit board having wiring layers of inner layers, and all of terminals electrically connected to wiring layers of the inner layers among the terminals arranged in the third region are electrically connected to the same wiring layer.
According to a still further aspect of the present invention, there is a semiconductor package having a plurality of signal wiring layers and a plurality of first and second power supply terminals, which are arranged on a principal plane of the semiconductor package, wherein at least one side of the inside and outside of a first region, in which the first power supply terminals are formed, is surrounded by the signal wiring terminals, and at least one side of the inside and outside of a second region, in which the second power supply terminals are formed, is surrounded by the signal wiring terminals.
The second region may be arranged within the first region, which may be spaced from the second region via a third region, and all of terminals arranged in the third region may be signal wiring terminals.
Preferably, the semiconductor package has multilayer wiring layers as inner layers, and all of terminals electrically connected to wiring layers of the inner layers among the terminals arranged in the third region are electrically connected to the same wiring layer.